Beijing , China -LRB- CNN -RRB- -- Dissident artist Ai Weiwei will not be allowed to publicly appeal a multimillion-dollar tax penalty the Chinese government says he owes , he said Thursday .

Ai told CNN by phone that Chinese tax authorities sent him a note March 27 telling him he will not be given a public trial but a `` written hearing . '' They sent him another note Thursday saying he must pay the 15 million yuan -LRB- $ 2.4 million -RRB- in back taxes he was already ordered to pay , and that he can make no further appeals .

Ai , who was found guilty of tax evasion last year , said he plans to sue the tax authorities .

Chinese authorities detained Ai for 81 days last year and later ordered him to pay the 15 million yuan in back taxes they said he owed through his company , Fake Cultural Development Ltd. .

Ai paid 8.45 million yuan -LRB- $ 1.3 million -RRB- late last year so he could contest the charges . Had he not paid the sum , he said at the time , his wife would have been jailed .

Ai 's family and human rights advocates have said they believe the Chinese government is targeting him for his criticism of the regime .

An internationally renowned artist , Ai 's works -- often with political undercurrents -- command hundreds of thousands of dollars . His 2010 installation at the Tate Modern in London involved 100 million porcelain sunflower seeds , each one hand-painted by specialists in China , spread on the floor of the museum 's large entrance hall .

Ai helped design Beijing 's iconic Bird 's Nest stadium for the 2008 Olympics , though he later spoke against the Games .

CNN 's Judy Kwon contributed to this report .

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Ai Weiwei says he will only get a `` written hearing ''

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China says he owes $ 2.4 million in back taxes

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His supporters say he 's being targeted for criticizing the government

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Ai is an internationally renowned artist